Fincher gives himself the task of a nearly three-hour murder-mystery with no definitive conclusion. The Zodiac Killer was never caught, so the film doesn't have the standard satisfactory conclusions of a normal whodunit. Instead, you leave the film feeling a little dirty, much like you did after seeing Fincher's other serial-killer film, the masterpiece Se7en.
The Zodiac Killer allegedly started his murder spree in 1968, although there are some suspected victims from as early as 1963. He would send letters to newspapers claiming his murders and taunting authorities with future crime sprees. The letters were sent between 1969 and 1974, with one last possible letter sent in 1978, although that letter's authenticity was questioned.
Zodiac focuses on different phases of the investigation. Jake Gyllenhaal plays Robert Graysmith, a political cartoonist at the San Francisco Chronicle. (Graysmith would later write some books on the killer.) Graysmith observes from the sidelines as newspaper employees try to decipher the Zodiac's cryptic puzzle letters, and begins "hovering" over the desk of writer Paul Avery (Robert Downey Jr.). It's Avery who would cover the Zodiac's crimes for the Chronicle, eventually receiving an ominous card with bloody clothing addressed specifically to him from the killer. The bantering of Graysmith and Avery reminds of Dustin Hoffman and Robert Redford in All the President's Men.
The first phase of Graysmith's involvement, as well as Avery's, slips into the background as the film turns to the investigation led by inspectors David Toschi (Mark Ruffalo) and William Armstrong (Anthony Edwards). The two do an excellent job of portraying earnest cops who, nevertheless, are getting nowhere with the case.
Graysmith later re-emerges, with Avery gone and the police at a dead end. His re-examination of the facts leads to extra attention on a primary suspect, Arthur Leigh Allen (hauntingly played by John Carroll Lynch). Graysmith discovers many coincidences involving Allen, although he was never brought up on charges and died in 1992.
The performances are all first rate. Gyllenhaal portrays Graysmith as somewhat of a geek, and the approach provides the film with much-needed comic elements. Downey Jr. continues to amaze, capturing a true sadness in Avery, a man whose career apparently spiraled downward after his time spent writing on the Zodiac Killer. Ruffalo, who has made a lot of dopey romantic comedies lately, gets a chance to show his substantial acting chops as Toschi, although his character is saddled with a few distracting quirks. (He likes to mooch other people's food.)
Some are saying that the film loses focus at times, spinning off into excessive characters with different men trying to solve the case of the Zodiac. Doesn't this make sense? I think Fincher made it part of his mission to show just how confused and unfocused authorities became trying to chase this nut. As the man evaded capture for nearly 40 years (he could still be alive), careers fell; lives and marriages were ruined; and reputations were destroyed. Fincher does an excellent job of bringing this aspect of the investigation across.
He also, not surprisingly, is masterful with the horrific parts. A sequence where a picnicking couple is viciously attacked is among the most painful movie scenes I have ever watched. A couple parked on a lover's lane, a woman kidnapped with her child and a victimized cab driver all add to the horror.
While the subject has been addressed before in other films (Dirty Harry based its murderer on the Zodiac), this film stands as the definitive treatment of the case. It leaves you with a bad aftertaste, shaken by the knowledge that a very sick person was never caught, and the effects of his crimes still linger.